Ingot mold



Jan. 18, 1944. E, GATHMANN 2,339,601

INGoT MOLD Y Film oct; 28,Y v1941 gmc/YM Patented Emu Gath'mann,

Gathmann Research Baltimore, Md.,` assignor to Incorporated,Catonsville, Md., a corporation of Maryland Application october 2s,1941, serial-N0. 416,871

s claims. (ci. ,2a-139) This invention relates. to ingot molds, and moreparticularly to metallic ingot molds having big-end-up ingot-formingchambers. this general class have been known in the art for many yearsand now are used extensively, particularly in the production of highquality steels. Many factors enter into the production of sound ingotsin molds of this class, and, aside from the Apreparation of the metalitself before it is teemed into the molds, which of course is importantin the making of any metal product, such factors are generally the crosssectional contour of the mold chamber, its vertical contour, and therelation of mold wall thickness to the chamber cross section atdifferent zones vertically of the mold.

Generally stated, it is fundamental, in view of prior art disclosures,for the thickness or heatabsorptive capacity of big-end-up mold walls tobe so related to the mold chamber cross section that ingot metal willcool and solidify progressively from bottom to top. Such a mold isshown, lfor example, in my early- Patent'Number 974,133,

granted November 1, 1910, and in many other patents to myself and toother inventors. The cross sectional area of a big-end-'up moldchamberbeing larger at the top than the bottom, the

inner surfaces of the mold walls naturally have an'upward-outward slantwhich, in itself, tends to make the walls of diminishing thickness andlessening heat-absorptive capacity progressively from bottom to top. Inmost prior art molds, this progressive diminishing of theheat-absorptive capacity has been augmented by slanting the wall outersurfaces upwardly-inwardly. In a few instances it has been proposed toprovide an upward-outward slant for wall outer surfaces, relying uponthe progressive increasing of the chamber cross section from bottom totop to bring about the desired cooling and solldiflcation of the ingotprogressively from bottom to top.

In my prior Patent Number 2,166,587, granted July 18, 1939, there isdisclosed and claimed a .big-endhup mold the inner or matrix wallsurfaces of which are differentially slanted upwardlys-outwardly frombottom to top; that is, the matrix surfaces have different degrees ofslant indifferent vertical zones, there being a higher -degree of slantin the lowermost side Wall inner surfaces than in the above andadjoining side wall inner surfaces. The outer surfaces of the moldwallsshown in Patent 2,166,587 are slanted upwardly and inwardly according tothe prevailing practice at the time of the invention disclosed in thepatent. The differential slanting of the mold wall inner surfaces hasbeen found to pro- MOldS 0f mote soundness and reduced lsegregation ofthe ingot metal, to reduce ingot surface defects, to

reduce crop loss, to facilitate initial reduction of the ingot in therolls, and to prolong mold life.

invention is to prohaving differentially An object of the present vide abig-end-up mold slanting side wall inner surfaces of the generalcharacter rections of extent of are so related to the slantlng indifferent vertical zones as to still further. promote the obtaining ofthe desirable physical charreferred to above and in which thedithe moldwall outer surfaces acteristics of an ingot produced in the mold.

Another object is to provide a mold of the general character referred toin which the directions of extent of the wall outer surfaces, and themold wall thickness in different zones, are

' so related to the chamber cross sectional area as to promote theproduction of sounder ingots. with the use of a lower ratio of moldmetal weight to ingot metal weight than it heretofore has been' possibleto use in the production of sound ingots.

In accordance with the invention, a big-end-upA mold havingdifferentially slanting wall inner surfaces has outer wall surfaceswhich preferably are free from the upward-inward slant heretoforecharacteristic of such molds. The wall outer surfaces may slant upwardlyand outwardly, but to a lesser degree than the lowermost portions of thewall inner surfaces.

In a preferred form, the upward-outward slant of the wall outer surfacesis substantially the same as the upward-outward slant of the wall innersurfaces above the lowermost inner surfaces.

' Thus, throughout a substantial part of the mold above its lowermostwall surfaces, the walls may be of substantially uniform thickness; asdistinguished from the lowermost walls of progressively diminishingthickness. Further, itis preferred, in accordance with the invention,that the ratio of the cross sectional area of the mold chamber to thecross sectional area of the mold walls at the bottom of the mold bear acertain relation, within a generally limited range, to the ratio of thecross sectional area of the mold chamber to the cross sectional area ofthe mold walls at the top of the mold; The relations be` tween theslants of mold wall surfaces, and ratios of chamber cross lsectionalarea to mold wall cross sectional area may vary in accordance withl thesize of the molds. VA mold embodying the invention in one form is shownin the accompanying drawing, in which:

Figure 1 is a vertical sectional view; and

Figure 2 is a top plan view.

inner wall surfaces 2 i j o The invention may be embodied in big-end-upmolds having differentially slanted side wall inner surfaces and crosssectional contours of various kinds. For the purposes of illustration,there is disclosed a cast iron mold M having a cross sectional chambercontour of the kind disclosed and claimed in my Patent 2,240,396,granted April 29, 1941. However, vertical mold wall contours formed invaccordance with the present invention may be embodied in molds notnecessarily of generally rectangular cross sectional contour. In

the present specication, the plural term walls" r main or body portionsare substantially straightand slant upwardly and outwardly from thelongitudinal axis of the mold chamber; but the surfaces 3* slant to agreater degree than the surfaces 4i. The relative amounts of slantandthe relative height of the more greatly slantedsurface 3 may vary independenceupon the horizontal cross section of the mold chamber, but thelower slanted surface 3a preferably should be between about twenty percent and fty per cent of the total length of the mold chamber, and

it should be slanted preferably two to twenty times as much per inch ofheight as the adjoining upper inner surface 4a. It usually isadvantageous to employ an extreme upper wall portion 5 having an innersurface 5u which is substantially vertically or parallel to the verticalaxis of the mold chamber.

Depending upon the size and` assaeoi progressively reduced rate ofcooling of the ingot metal-brought about by the absorption of heat bythe wall portion 4 is due to increase of the mold chamber (and ingot)cross-sectional area v progressively from botto'n to top, rather than todecreasing mold wall thickness. However, in order to avoid various kindsof iiaws and unsoundness in the lowermost portion of an ingot, theinverse cooling gradient from bottom to top of the wall portions 3should be rather steep, and

in molds constructed in' accordance with the present invention thedesired relatively rapid decrease in the A cooling capacity from bottomto top of Vthe wall portions 3 is assured by forming the inner surfacesof the wall portions 3 with a marked upward-outward slant, even thoughthe associated outer 4wall surfaces are formed without upward-inwardslant.

Molds constructed as described herein have been used in the productionof large tonnages of ingots of sounder structure than heretofore hasbeen generally obtainable. Aside from the vcapability of producingimproved ingots per se,

. molds embodying the invention have an addicross section of the moldchamber, the section 5 may be of varying length which should be somewhatless than the maximum cross-sectional dimension of 'the mold chamber andpreferably should be between about ve percent and twenty per cent of themold chamber height. The bottom 2 is of necked-in concavo-convexcontour, preferably of the kind disclosed and claimed in my Patent2,242,703, granted May 20, 1941.

In accordance with the present invention, the outer surfacesof the moldside wall portions 3, 4, and 5 preferably are free from upward-inwardslant. In the form shown, the outer surfaces 6 are straight and have aslight upward-outward slant. Ihe relation of the outer surfaces 6 to theinner surfaces 3, 4a, 5a of the wall portions 3, 5. and 5 is such thatthe thickness of the lowermost side wall portions 3 progressivelydiminishes to a marked degree from bottom to top, whereas the wallportions 4 and 5 lare of substantially uniform thickness throughouttheir vertical extents, although a slight progressive diminishing ftremendous savings possible. perishable, a life of eighty heats usuallybeing ore, less scrap re-melting, and less space and in thickness frombottom to top of these wall portions will not actually be harmful. Majordimensions of the mold shown generally to scale in the accompanyingdrawing are marked on Figure 1, it being understood that, although themold shown is a commercial embodiment of the invention, the dimensionsare not intended to `be used by way of limitation. The outer surfaces Siof the walls slant upwardly-outwardly only a very little less per inchof height than the inner surfaces 4 of the wall portions 4, and thethickness of the wall portions 4 and 5 therefore is substantiallyvuniform throughout. Thus. the

tional f and very important advantage in that, for forming and properlycooling an ingot of a given weight and shape, they can be made of lessmold metal than heretofore was possible. Extensive commercial use ofmolds embodying the present invention has shown that, for a given sizeingot, and with other factors being'generaliy the same, molds havinginner and outer side surface contours related as disclosed herein andweighing twenty percent less than prior art molds having similar innercontours are capable of producing ingots which are fully as sound as orsounder than ingotscast in the heavier molds of the kind heretoforeknown in the art. Commercial use also has demonstrated that thelightening of the molds in accordance with the present invention doesnot shorten the mold-life appreciably.

It will be apparent that the lightening of molds in accordance with thepresent invention makes Ingot molds are considered good. After moldshave become pitted, cracked, eroded, or otherwise rendered unfit forfurther service, they must be scrapped and re-melted.Consequently,lightening of the mold not only results in a direct saving in the costof equipment used in the production of ingots, but also effects amultitude of substantial indirect savings such as less transportation ofweight carrying capacity in transporting the molds from the foundries tothe steel plants.

It is necessary that the molds be heavy enough, particularly at thebottom, to effect proper chilling and solidication of the ingot metal.In the mold shown inthe drawing, the ratio of the -mold cross-sectionalarear to the chamber cross-sectional area is about 1.68 at the level Cat the bottom of the wall portions 3, and is about 1.03 at the level Aat the top of the wall portions 4 and 'thereabova For producing soundingots in light and therefore economical molds having differentiallyslanted side wall inner lsurfaces and side wall outer surfaces free fromupward-inward slant, the ratio of mold wall cross-sectional area assacoistood that changes may be made without departing from the invention asdefined in the claims.

I claim: 1. A metallic ingot mold comprising bottom and side wallshaving outer surfaces and inner tions, comprising from twenty per centtov fifty per cent of the total side wall -inner surface length, beingslanted upwardly and outwardly to a materially greater degree than theadjoining intermediate opposed side wall inner surface sections, andsaid intermediate opposed side wall inner sections being slantedupwardly and outwardly more than the opposed extreme upper side wallsurface sections, the outer surfaces of said opposed side walls. frombottom to -top being lfree from upward-inward slant, the ratio of themold wall cross-sectional area to the chamber cross-sectional area beingapproximately 1 to 1 at the top oi' the mold and being approximately 1.7to 1 at the bottom of the mold, the ratio of the mold wallcross-sectional area to the chamber cross-sectional area at the bottomof said lowermost sections thus being greater than but not more thantwice as great as the ratio of the mold wall cross-sectional area to thechamber cross-sectional area adjacent the top of the mold. i

2. A metallic ingot mold comprising bottom and side walls having outersurfaces and inner surfaces, the latter defining a big-end-up ingotforming chamber, the mold walls progressively decreasing in thicknessfrom the bottom upwardly adjacent opposed lower inner tide surfaceportions and being of substantially uniform thickness adjacent opposedinner side surface portions aboveand adjoining said lower opposed innerside surface portions, the ratio of the mold wall cross-sectional areato the chamber crosssectional area being approximately l to 1 at the topof the mold and being approximately 1.7 to 1 at the bottom of the mold,the ratio of the mold wall cross-sectional area to the chambercross-sectional area at the bottom of said lowermost sections thus beinggreater than but not more than twice as great as the ratio of the moldwall cross-sectional area to the chamber cross-sectional area adjacentthe top ofthe outer and inner surfaces of which both define a big-end-upcontour, the ratio of the crosssectional area of the walls to thecross-sectional area of the chamber in the upper part of the mold beingapproximately 1 to 1 and increasing towards the bottom of the mold, theratio of the mold wall cross-sectional area to the chambercross-sectional area at the bottom of the mold being vgreater than butnot more than twice asgreat as the ratio of the mold wall`cross-sectional area to the chamber cross-sectional area adjacent thetop ofthe mold.

4. A necked-in bottom metallic ingot mold, the outer and linner surfacesof which both define a big-end-up contour, the outer surfaces having asingle yslant from top to bottom and the inner surfaces having at leasttwo degrees of slant, the greatest degree being in the lower portion ofthe chamber, the ratio of the walicross-sectional area to the chambercross-sectional area being approximately l to 1 in the upper part of themold and the ratio of the wall cross-sectional area to chambercross-sectional area in the lower part of the mold being substantiallygreater than but less thanvtwice as great as in the upper portion.

5. A metallic ingot mold, the outer wall surfaces and inner chambersurfaces of which both denne a big-end-up contour, at least two opposedinner surfaces being in at least two sections from bottom to top, thelowermost section, comprising from about 20% to about 50% of the totalinner side wall length, being slanted outwardly to a materially greaterdegree than the adjoining upper wall portions, and the outer surfaces ofthe mold having an approximately uniform outward slant from bottom totopI the ratio of the.wall cross-sectional area -to the chambercross-sectional area in the upper part 'of the mold being approximately1 to 1 and the ratio of the wall cross-sectional area to chambercross-sectional area in the lower part of the mold being substantiallygreater than but less than twiceas great as in the upper portion.

6. A metallic ingot mold, the cuter and inner surfaces of which bothdefine a big-end-up contour, at least two opposed inner surfaces havingv at least two degrees of slant, the greatest degree being in thelowermost portion, vand the outer surfaces of the mold having anapproximatelyv uniform slant, the cross-sectional .area of the walls atthe upper portion of the. mold beingV approximately equal to the crosssectionalv area of the chamber at this portion, and the ratio of thewall cross-sectional area to chamber crosssectional area in the lowerpart of the mold being substantially greater than but less than twice asgreat as in the upper portion.

f EMIL GATHMANN.

